TABLE OF CONTENTS The frequency range of interest to electronic warfare (EW) applications extends from 100 MHz to 18 GHz. Some long-range searching radars operate under 2 GHz, and one can consider EW operations nominally from 2 to 18 GHz. An EW receiver usually has an instantaneous bandwidth of .5 to 4 GHz, which is limited mainly by hardware constraints. This receiver is often referred to as the intermediate frequency (IF) receiver, which is time-shared to cover the 2- to 18-GHz frequency range. Generally, it is difficult to build an IF receiver with wide instantaneous bandwidth. Even if one could build such an IF receiver, the digital processor following the receiver would not be able to process the data in near real time. As a result, some of the data will be ignored by the processor. In this case, the digital processor limits the bandwidth capability of the IF receiver. In order to increase the bandwidth of the IF receivers, both receiver and processor technologies must be advanced.
To simplify the discussion in this chapter, let us assume that an IF receiver has approximately 1 GHz instantaneous bandwidth, which means any signal in the bandwidth will be intercepted. In order to cover the frequency range of interest, the input frequency range will be broken into many parallel channels (referred as channelization) and each channel will be frequency converted to match the input frequency range of the IF receiver.
In conventional analog receivers, the input frequency of 2 to 18 GHz is...
